A predicate pronoun is any pronoun that is part of the predicate. A predicate is the part of a sentence that includes the verb and the words following it that relate to that verb.
Answer:
I think its D, if its not right then it could possibly be C.
Vain is the correct answer. Plug in each word given into the sentence and then read it to see if the sentence makes sense.
"We may try in credibility to solve our problems on our own.." Credibility is incorrect.
"We may try in predict to solve our problems on our own.." Predict is incorrect.
"We may try in forgive to solve our problems on our own.." Forgive is incorrect.
"We may try in vain to solve our problems on our own.." Vain is correct!
Hope this helps! (: